This invention relates primarily to software. In particular, it relates to electronic mail ("e-mail") systems, and to techniques in such systems for guaranteeing the delivery of messages.
In an e-mail system, it is sometimes essential to deliver a message to a recipient before a certain time, or just to assure delivery of the information. For example, the addressee of a message might be scheduled to give a presentation at a set time, and the sender must inform the addressee about the availability of a product, a change in the presentation, or some other information before the start of the presentation. Other examples are the scheduling of meetings, arranging for the delivery of agreements, etc. Conventional e-mail systems operating across company or local area network boundaries do not allow the senders of messages to determine whether their messages have been read. As a result, the sender of a message often must telephone the recipient to verify that the needed information has not only arrived at the recipient's system, but has been reviewed by the recipient.
In conventional e-mail systems, messages are delivered in "envelopes" which are then "opened" by the recipient to be read. Many e-mail systems allow a sender to check a separate database to see if a message has been read. Some proprietary e-mail systems include an acknowledgement feature that allows the recipient's e-mail system to send a notification to the sender when the recipient has opened the message. E-mail systems with acknowledgement features include Apple Computer's AppleLink.TM. and the International Business Machines' V-Net System.TM..
Prior art e-mail systems of this type have at least two disadvantages. First, such e-mail systems do not work across proprietary boundaries. Thus, a sender of a V-Net message cannot address a user of some other system and receive an automatic acknowledgement notification. Second, even when such systems are used wholly within a proprietary environment itself, the sender of a message must remember to look for the acknowledgement notification. Furthermore, the need to take corrective action, for example by telephoning the recipient, faxing him a copy of the message, etc., only arises when the acknowledgement notification has not arrived at the sender's system before the deadline. The absence of receiving a notification, particularly among the many notifications which are otherwise received and not received, is a subtle event and easily overlooked.